This project uses data from the third National Health and Nutrition Examination Survey (NHANES III, 1988-84), linked to birth certificates for sample children ages 2-83 mo (coordinated by Dr. Overpeck through and interagency agreement with NCHS/CDC) to explore the health consequences of intrauterine growth. The latest analyses have focused on breastfeeding and risk of overweight, motor and social development (MSD), and early childhood caries (ECC). Analyses have been completed related to infant feeding and MSD and have been initiated for ECC. Since it has been suggested that breastfeeding is protective against overweight and there is a dose-dependent effect of its duration, children ages 3-5 y were categorized by body mass index (kg/m2) as being overweight (> 95th percentile) based on cutoffs from the new NCHS/CDC growth charts. Adjusting for confounders, there was no significant risk of being overweight (AOR=0.84, 95% CI 0.62-1.13) and no clear dose-dependent effect of the duration of full breastfeeding. Breastfeeding continues to be strongly recommended, but may not be as effective as moderating familial factors, such as dietary habits and physical activity, in preventing children from becoming overweight. In other analyses, we determined the independent effects of birth weight and gestational age on MSD, using an age-appropriate scale from 2-47 mo. Three percent of the infants and children were born preterm LBW and 2.2% term LBW. Adjusting for confounders, preterm LBW children still had lower MSD scores (-1.5 +/- 0.3 points, p<0.0001), as did term LBW children (-0.8 +/- 0.4 points, p< 0.03). LBW status and preterm delivery were associated independently with small, but measurable delays in MSD through early childhood. Even for children only moderately LBW or moderately preterm, perinatal factors should be considered in association with other known risk factors for developmental delays in determining the need for clinical follow-up and evaluation.